1. Field of the Invention
This invention generally relates to a direct type backlight unit, and more particularly to a direct type backlight unit having a supporting pin formed integrally therein.
2. Description of the Related Art
Due to the advance of electronic technology, especially for the popularity of portable electronic products, the requirements of light, compact and low-energy consuming display are gradually increasing. With the advantages of low-energy consuming, low-heat dissipation, light weight and non-luminescence, liquid crystal displays (LCD) have been widely used in the electronic products and even have replaced the traditional CRT displays.
In general, a liquid crystal display usually comprises a backlight unit for providing light to its liquid crystal panel. However, the liquid crystal display may use different kinds of backlight units depending on its use and size. These backlight units mainly include two types, i.e. a direct back light type (or direct type) and an edge light type. The present invention herein is related to the direct type backlight unit, and thus only the direct type backlight unit will be described in following descriptions.
Referring to FIG. 1, it shows an exploded schematic view of a liquid crystal display 100 having a direct type backlight unit in the prior art. The liquid crystal display 100 includes a backlight unit 102, a set of optical films 104, a liquid crystal panel 106 and a frame 108. The backlight unit 102 is disposed under the liquid crystal panel 106 for distributing the light from a light source uniformly over the surface of the liquid crystal panel 106. The backlight unit 102 comprises a metal housing 103 and lamps 100, such as cold cathode fluorescent lamps (CCFL), disposed at the base of the metal housing 103. The set of optical films 104 is disposed between the backlight unit 102 and the liquid crystal panel 106 and includes a diffuser 104a disposed upon the backlight unit 102 and a plurality of optical sheets, such as a diffusing sheet 140b and a prism sheet 140c, disposed on the diffuser 104a. The frame 108 is disposed upon the liquid crystal panel 106 and the set of optical films 104 and connected to the backlight unit 102 so as to fix the liquid crystal panel 106 and the set of optical films 104 on the backlight unit 102. FIG. 2 shows a cross-sectional view of the assembled liquid crystal display 100 taken along line A—A in FIG. 1.
The lamps 110 are spacedly disposed on the cavity 105 formed by the metal housing 103 and positioned under the display area of the liquid crystal panel 106 so as to distribute the light uniformly over the surface of the liquid crystal panel 106. Further, since the lamps 110 need to keep a certain distance from the diffuser 104a, at least one supporting pin 112 is required to be disposed on the base 103a of the metal housing 103 for supporting the diffuser 104a such that the lamps 110 can keep a fixed distance from the diffuser 104a. 
In the prior art, the supporting pin 112 is a white or transparent conical pin, which is typically made of polycarbonate (PC) or PMMA by the injection molding process. In addition, the base 103a of the metal housing 103 is covered with an adhesive film (not shown), and the supporting pin 112 adheres to the base 103a of the metal housing 103 by the adhesive film.
However, the reliability of such an adhesion manner to fix the supporting pin 112 on the base 103a of the metal housing 103 is usually poor.
Accordingly, the present invention provides a direct type backlight unit having a supporting pin formed integrally therein so as to solve the reliability problem of the supporting pin.